1. Field of the Invention
The present disclosure relates to electrically heated filter screens, and more particularly to electrically heated filter screens with metal protective layers for aircraft fuel systems.
2. Description of Related Art
Gas turbine engine fuel systems operate in wide range of environmental conditions. In extremely cold operating environments such fuel systems are susceptible to ice formation in fuel tanks, conduits, valves, and other system components. Ice formation can occur when either fuel or water contaminating the fuel is exposed to low temperature for extended time periods.
To combat icing, electrically heated filter screens can be provided within the fuel system. Electrically heated filter screens operate to capture and melt ice conveyed through the fuel system prior to it becoming lodged in the system and affecting engine operation. Conventional electrically heated filter screens may include a heater element coated with a ceramic layer. The ceramic layer functions to electrically insulate the heater element from fuel flowing through the screen and to provide efficient thermal conductivity between the heater element and fuel traversing the electrically heated filter screen.
Conventional electrically heated filter screens have generally been considered satisfactory for their intended purpose. However, there is a need for electrically heated filter screens resistant to damage from ice, contamination and debris entrained in fuel as it flows through the fuel system. There also remains a need for electrically heated filter screens that are easy to make and use. The present disclosure provides a solution for these problems.